Illumination Adaptation in a Multi-Wavelength Opto-Electronic Patch Sensor

Sensors

Matthew Hayes¹  Samah Alharbi²  Panagiotis Blanos²  Sijung Hu²  David Mulvaney²  Liangwen Yan³  Yue Yu³ 

[1] Evonetix Limited., 9a Coldham’s Business Park, Norman Way, Cambridge CB1 3LH, UK;School of Mechanical, Electrical and Manufacturing Engineering, Loughborough University, Loughborough LE11 3TU, UK;School of Mechatronic Engineering and Automation, Shanghai University, Shanghai 200444, China;

关键词: multi-wavelength opto-electronic patch sensor;    heart rate;    adaptive algorithm;    photoplethysmographic;   

DOI  :  10.3390/s20174734

来源: DOAJ

【 摘 要 】

In capturing high-quality photoplethysmographic signals, it is crucial to ensure that appropriate illumination intensities are used. The purpose of the study was to deliver controlled illumination intensities for a multi-wavelength opto-electronic patch sensor that has four separate arrays each consisting of four light-emitting diodes (LEDs), the wavelength of the light generated by each array being different. The study achieved the following: (1) a linear constant current source LED driver incorporating series negative feedback using an integrated operational amplifier circuit; (2) the fitting of a linear regression equation to provide rapid determination of the LEDs driver voltage; and (3) an algorithm for the automatic adjustment of the output voltage to ensure suitable LED illumination. The data from a single centrally-located photo detector, which is capable of capturing all four channels of back-light in a time-multiplexed manner, were used to monitor heart rate and blood oxygen saturation. This paper provides circuitry for driving the LEDs and describes an adaptive algorithm implemented on a microcontroller unit that monitors the quality of the photo detector signals received in order to control each of the individual currents being supplied to the LED arrays. The study demonstrated that the operation of the new circuitry in its ability to adapt LED illumination to the strength of the signal received and the performance of the adaptive system was compared with that of a non-adaptive approach.

【 授权许可】

Unknown